1. Field of the Invention
The subject matter disclosed generally relates to the field of semiconductor lasers.
2. Background Information
Semiconductor lasers are used in a variety of system applications. For example, semiconductor lasers are used as a light source in fiber optic communication systems. Laser diodes emit a laser beam from either the edge of the diode die or the surface of the die. Commercially available surface emitting dies contain a vertical cavity and are commonly referred to as Vertical Cavity Surface Emitting Lasers (VCSELs).
Because edge emitting diodes emit the beam from the edge of the semiconductive die, each die must be cut from the wafer before being tested. Conversely, VCSELs, being surface emitting, can be tested in wafer form. Testing at the wafer level reduces the cost associated with testing the laser diodes.
Unfortunately, VCSELs emit a relatively low power laser beam. Consequently, the use of VCSELs has been limited to short optical links. Additionally, most commercially available VCSELs emit light at 850 nanometers (nm). Fiber optic cables strongly disperse and absorb 850 nm light. Edge emitting diodes can generate light at 1310 or 1550 nm which are less affected by absorption and dispersion within a fiber cable.
There have been attempts to integrate internal mirrors within an edge emitting laser diode so that the laser beam emits from the top surface of the diode. For example, ion-beam milling processes have been used to form inclined reflective mirrors within an edge emitting diode. Ion-milling is a relatively inaccurate process that produces rough reflective surfaces. Consequently, such an approach does not have a commercial application.